UA124447U - METHOD OF ATTACHMENT OF OIL AND GAS BOLTS WITH ABNOMINALLY LOW PLASTIC PRESSURE - Google Patents

Abstract

A method of securing oil and gas wells with abnormally low reservoir pressure involves pumping into the enclosure space over the entire length of the casing column, which does not form a rock, and subsequent isolation of the column space from the enclosure by cementing the casing in the lower 10-10 the required portion of the stone-forming cement mortar into the sheltered space after the stone-free cement mortar. Previously, in the well, the walls of the productive layer are reinforced with a thin cement layer due to the chemical interaction of silicate rocks, such as sandstones, with lime or carbonate and sulfate rocks, such as chalk and anhydrite, with liquid glass, by bathing with viscous-elastic liquids. respectively lime or liquid glass. Then pumped into the recessed space of the well for the entire length of the casing, a stone-forming mortar, which is a hydrophobic thermodynamically stable viscous-plastic material containing bitumen dissolved in hydrocarbons, insoluble in hydrocarbons and hydrocarbons and organic water-soluble colloids. Then in the lower part of the sheltered space at a height of 50-150 m is injected with a portion of cement mortar, which forms a cement stone, to secure the casing.

Description

A useful model belongs to the oil and gas industry, namely to methods of fastening oil and gas wells.

It is known that the cement stone in the backspace of the well performs two main functions - maintaining the casing in a suspended state, as well as preventing the occurrence of backflow of fluids. The use of the generally accepted technology of fastening columns using cement mortars, which ensure the formation of a strong stone, eventually leads to a violation of the tightness of the well according to the physical principle: a solid body under the action of loads exceeding the strength limit of the material is destroyed with the formation of cracks. This leads to the loss of well tightness. Therefore, the function of a sealed space should be performed by an additional tamponage material that forms a plastic body and is thermodynamically stable. Bitumen dissolved in hydrocarbons, in combination with various impurities, turned out to be the most suitable and effective material for performing the function of such a sealant.

For the first time, such a technical solution was proposed in the invention (see RF patent No. 2068489.

MKI 7 E21B 33/13. The method of fixing wells. A.O. Vasylchenko (Ukraine). Application 92003771/03. Announced on 10/26/92. Publ. 27.10.96). According to this patent, the method of fastening wells consists in alternately pumping into the backspace of the well a tamponage (cement) solution that forms a stone and a tamponage solution that does not form a stone, but is a hydrophobic plastic body that contains a weighting agent and particles of undissolved bitumen.

The method provides reliable (100 95) well sealing.

The disadvantage of the method can only be considered that it does not provide for the protection of formations with abnormally low pressure from the influence of excessive pressure of the slurry column.

Another method of solving the problem of ensuring the tightness of wells is proposed in the work (see Luban V.3. "The effect of drilling and plugging solutions on the stability of the walls of wells in chemogenic sediments".

Gubkin. - M. - 1979. - 25 p.). According to the method, the hydrocarbon-based tamping solution is prepared by mixing cement with water and a setting time regulator and then dispersing the cement solution in diesel fuel containing surfactants, such as sulfonol,

Zo and a filtration regulator, for example, highly oxidized bitumen, and the water released during the interaction of the components is removed, and then the prepared tamponade solution is pumped into the closed space of the well and is kept for 30 days or more until the formation of cement stone.

The above method, for the implementation of which hydrocarbon-based cement mortars were created according to the author's certificates of the USSR MoMo 502111, 502852, 684128, satisfactorily prevented the occurrence of backflows in the well.

The disadvantage of this method is, first of all, the long duration of the process, due to the fact that the formation of a mineral binder occurs only after the destruction of the inverted emulsion and the appearance of free water in the system. Additional disadvantages of the method are the complexity of the technology of preparing the tamponage solution, associated with the need to remove excess water, as well as the high consumption of expensive diesel fuel.

A well-known method of fastening oil and gas wells, chosen as a prototype (see patent

RF Mo 2046926. IPK 6 E21B 33/14. Authors Chernomyrdin V.S. and other. Application 49444154/03.

Announced on 04/29/91. Publ. 27.10.95), which includes pumping a clay solution (a tamponage solution that does not form stone) into the column space along the entire length of the casing string, isolating the column space from the column space by cementing the casing string in the lower part within one pipe by pushing the necessary portion of cement solution into a closed space following a clay solution that contains dry granules consisting of clay and polyacrylamide. Injection of the viscous-plastic clay solution is carried out during the time before complete hydration and disintegration of the granules.

The method of fastening oil and gas wells according to the prototype prevents the formation of cracks in the plugging material in the backspace and to a certain extent reduces the probability of overflows.

The disadvantage of this method is the presence of a significant amount of water in the backfill material, which, when gas enters from the productive reservoir, leads to the formation of a water-clay-methane system (as in clay diapirs), in which extremely high pressure accumulates, capable of deforming the casing.

In addition, the clay solution weighted with clay granules has a density of the order of p-1200 kg/m3, which leads to a great repression on the productive layers.

The purpose of this useful model is to prevent the occurrence of hydraulic fracturing of formations with abnormally low pressure followed by the absorption of plugging solution, complete exclusion of backflow of fluids, simplification of technology and reduction of costs for fixing the well.

To solve the given problem, a well-known method of securing oil and gas wells with abnormally low formation pressure is proposed, which includes pumping into the casing space along the entire length of the casing a plugging solution that does not form stone, and the subsequent isolation of the column space from the casing by cementing the casing in the lower part to a height of 8-10 m by pushing the necessary portion of stone-forming backfill solution into the backfill space, following the non-stone-forming backfill solution, according to a useful model, the walls of the productive layer are previously strengthened with a thin cement layer due to the chemical interaction of silicate rocks, such as sandstones, with lime or carbonate and sulfate rocks, such as chalk and anhydrites, with liquid glass by installing a bath of viscoelastic liquids containing lime or liquid glass, respectively; then, a non-stone-forming tamponade solution is pumped into the backspace along the entire length of the casing string, which is a hydrophobic, thermodynamically stable visco-plastic material that contains bitumen dissolved in hydrocarbons, bitumen particles not dissolved in hydrocarbons, as well as impurities of quicklime and organic water-soluble colloids; and then in the lower part of the columned space to a height of 50-150 m, a portion of tamponage solution, which forms a cement stone, is pumped to fix the casing column.

Experience in drilling wells in conditions of abnormally low formation pressures, for example on

Shebelinsky GKR, shows that as a result of the use of lime-based drilling fluid on the walls of the productive formation, a cement layer is formed, which significantly increases the strength of the sandstone, prevents hydraulic fracturing of the formation during the initial opening and cementing of the column, and the natural permeability of the reservoir is completely preserved during the completion of the well (see Vasylchenko A. New technologies in the construction of oil and gas wells / A. Vasylchenko - baagtgikep: I AMVEVT Asadetis Rybiiznipa, 2012. - 104 p). The same result can be obtained by installing a lime bath in the form of viscous

From elastic composition. For these reasons, it is advisable to include the operation of strengthening the walls of the well into the complex technology of fastening the well. In addition to prevention of absorption, this technological operation ensures full preservation of the natural permeability of the collector.

The experience of using cement mortars based on hydrocarbons shows that the hydrocarbon-bitumen system reliably prevents the occurrence of backflow both at the stage of hardening of the cement stone and during the long-term operation of the well.

This allows this technical solution to use the installation of bituminous plastic material along the entire length of the sealed space, and not only in the form of individual bitumen packers, as provided for in the patent of the Russian Federation Mo 2068489. In addition to reliable sealing, the use of bituminous plastic material instead of cement simplifies the fastening technology, reduces costs, makes it possible to carry out single-stage fastening of production columns and allows to remove casing pipes in case of liquidation of the well.

The increase in the interval in the sealed space to 50-150 m, which is fixed with cement mortar, is due to the fact that the technical possibilities of installing a portion of cement mortar with a volume of 0.2-0.3 m3 in the interval of 8-10 m from the bottom of the casing column, as in the patent RF Mo 2046926, is a complex operation that requires special equipment.

When implementing the proposed complex technology of fastening wells, it is advisable to use the complex reagent according to the application for utility model и201708379 for the preparation of a tamponage solution that does not harden, because the complex reagent contains all the necessary components.

In order to reduce the costs of preparing a tamponage solution that does not form stone, it is suggested to use oil instead of diesel fuel.

Example of implementation of method 1.

The well was drilled with a bit of 9,215.9 mm on polymer-potassium drilling fluid to a depth of 2,500 m and revealed a gas-bearing layer represented by sandstone in the interval of 2,476-2,485 m with a reservoir pressure of Rol-12.5 MPa. An operational column of 0 168 mm was lowered into the well. Next, 2 m3 of visco-elastic composition (according to Ukrainian patent 32247), which additionally contained 5 95 lime, was prepared in the cementing unit and pumped into the interval of occurrence of the productive layer. On the surface, the calculated amount of tamponage solution, which does not form stone, was prepared by mixing the complex reagent according to the patent application bo i201708379, one of the modifications of which contains powdered bitumen - 43 95, carbon-alkaline reagent -

40 95, starch - 2 95, quicklime - 5 95, with oil in a mass ratio of 1 to 2. Before pumping into the well, 10 95 of a complex reagent in the form of a powder was added to the tamponage solution, which does not form stone, in order to form a hydrophobic plastic body in the closed space. After the visco-elastic composition was left to stand for 8 hours, 40 m3 of non-stone-forming plugging solution was pumped into the closed space of the well, followed by 2.5 m3 of cement mortar, 0.5 m3 of visco-elastic buffer (according to the patent Ukraine 32247) to prevent mixing and further polymer-potassium drilling fluid. There was no absorption of tamponage solution. The results of the acoustic caratage showed the high quality of the mounting of the column.

Example of implementation of method 2.

The well was drilled with a bit of 9,215.9 mm on polymer-potassium drilling fluid to a depth of 2,200 m and revealed a gas-bearing layer represented by chalk in the interval of 2,064-2,184 m with a reservoir pressure of Rall-11.2 MPa. An operational column of 0 168 mm was lowered into the well. Next, 2 m3 of visco-elastic composition (according to Ukrainian patent 32247), which additionally contained 10 95 of liquid glass, was prepared in the cementing unit and pumped into the interval of occurrence of the productive layer. On the surface, the calculated amount of tamponage solution, which does not form stone, was prepared by mixing the complex reagent according to the patent application i201708379, one of the modifications of which contains powdered bitumen 43 95, humate-alkaline reagent - 40 95, starch - 2 95, quicklime - 5 95, with oil in a mass ratio of 1 to 2. Before pumping into the well, 10 95 of a complex reagent in the form of a powder was added to the plugging solution, which does not form stone, with the aim of forming a hydrophobic plastic body in the trapped space. After the visco-elastic composition had been kept for 8 hours, 38 m3 of non-stone-forming plugging solution was pumped into the closed space of the well, followed by 2.5 m of cement mortar, 0.5 m3 of visco-elastic buffer (according to the patent of Ukraine 32247) to prevent mixing and further polymer-potassium drilling fluid. There was no absorption of tamponage solution. The results of the acoustic caratage showed the high quality of the mounting of the column.

Implementation of the proposed method will allow to significantly increase the efficiency of oil and gas well construction, reduce costs for fastening columns, eliminate

Due to the emergence of immigration flows.

Claims (1)

USEFUL MODEL FORMULA A method of securing oil and gas wells with abnormally low reservoir pressure, which includes pumping into the casing space the entire length of the casing of a non-stone-forming plugging solution, and the subsequent isolation of the casing space from the casing by cementing the casing in the lower part to a height 8-10 m by pushing the necessary portion of the stone-forming backfill solution into the backspace following the non-stone-forming backfill solution, which is distinguished by the fact that the walls of the productive layer are previously strengthened in the well with a thin cement layer due to the chemical interaction of silicate rocks, for example, sandstones with lime or carbonate and sulfate rocks, for example chalk and anhydrites, with liquid glass by installing a bath of visco-elastic liquids containing lime or liquid glass, respectively; then, a non-stone-forming tamponade solution is pumped into the backspace of the well along the entire length of the casing string, which is a hydrophobic, thermodynamically stable visco-plastic material that contains bitumen dissolved in hydrocarbons, bitumen particles not dissolved in hydrocarbons, as well as quicklime impurities and organic water-soluble colloids; and then in the lower part of the columned space to a height of 50-150 m, a portion of tamponage solution, which forms a cement stone, is pumped to fix the casing column.